1. Field of the Invention
The invention relates to a system for presenting a program to a user. More particularly, the invention relates to a method and a system for storing audio/video programs on a storage device for presentation to a viewer.
2. Description of the Related Art
An exemplary system for storing audio/video (A/V) programs is a personal video recorder, hereinafter referred to as PVR. Similar to a conventional video cassette recorder (VCR), a PVR is coupled to a monitor or a television set in a viewer's home and receives broadcast signals via a coaxial cable, a satellite dish or an antenna for terrestrial radio frequency (RF) signals. Often, a PVR is also coupled to a set top box. A PVR includes a hard disk drive with a storage capacity of between 20 GB and 80 GB that allows recording of up to 80 hours of television programming.
In order to store such large quantities of A/V programs, the A/V programs are usually compressed. That is, an encoder compresses and encodes an A/V program prior to storing, and a decoder decompresses and decodes the A/V program during playing back the A/V program. The encoder outputs a stream of program data that has a reduced bit rate and a reduced redundancy. The encoder and decoder usually operate in accordance with international standards and apply a compression process defined by the Moving Picture Expert Group (MPEG), e.g., MPEG-2, or by the International Telecommunications Union (ITU), e.g., the H.263 standard, that define uniform requirements for coding and decoding of program data.
For instance, the MPEG-2 compression of an A/V program by an MPEG-2 encoder results in a single compressed A/V program, which is referred to as “single-program elementary stream.” The MPEG-2 encoder packetizes the single-program elementary stream to generate a packetized elementary stream (PES). An MPEG-2 program multiplexer multiplexes a group of packetized elementary streams, i.e., a plurality of A/V programs, into a “transport stream.” The transport stream includes multiple series of fixed-size data packets and represents the plurality of A/V programs. Each data packet comprises a payload and a header that includes packet identification (“PID”) values.
The PVR stores the transport stream sequentially on the hard disk drive. Likewise, during playing back of an A/V program, the PVR retrieves the transport stream sequentially from the hard disk drive. The sequential management of the transport stream requires a high bandwidth and complicates the deleting of individual A/V programs. Thus, there is a need for an improved technique for storing and retrieving A/V programs.